Cutting attachment for sewing machines



Patented June 14, 1949 CUTTING ATTACHMENT FOR SEWING MACHINES Victor J. Sigoda, Great Neck, N. Y., assignor to Man-Sew Corporation, New York, N. Y., a corporation of New York Application November 5, 1946, Serial No. 707,895

9 Claims.

This invention relates to cutting devices for sewing machines, more particularly to shear action' cutters incorporated in sewing machines and adapted to sever one or more plies of material in a continuous manner as they proceed through the machine in the process of stitching.

The class of work to which the device of the invention is applicable is, generally, the sewing together of two or more pieces of fabric under circumstances where it is desired to trim or out of? surplus material along a line parallel to the line of stitching as in the case, for example, of applique, insertion, border trimming and like work. As a more specific example, there is a large volume of work, in the ladies undergarment and other fields, in the stitching of lace borders and insertions to the base fabric of the garment. By handmethods, after the lace has been sewed to the base fabric those portions of the latter which underlie the lace are cut away with scissors alongside of the machine stitching. The sewing in this "class of Work is generally done on zigzag sewing machines and the device of the invention is particularly adapted for use there with. However, its application is not limited thereto as it may: alsobe used with straight-away stitching.

Theprimary object of the invention is to provide a simple, rugged, efficient and inexpensive cutting device adapted to cut fabric being sewed simultaneously with the stitching operation,

Another. object is to provide a shear-action cutter capable of severing the goods immediately in front of the needle and inside the line of stitching. which is formed by a zigzag sewing machine so-that no margin of goods exists outside of the stitching upon completion of the sewing.

Another object'isto provide a shear actioncutting device which may readily be attached to existing machines, without any substantial altera- .tion in the machine, by simple replacement of parts.

A. further-object is to provide a shear action cutter capable of prolonged high speed operation without getting. out of adjustment and embodying. simpleyet effective means for automatically compensating for wear of the shearing blades.

A still further object is to provide simple means for adiusting the tension between the shearing blades.

Another object. is to provide a cutting device in which the cutting blades are readily removable for sharpening or replacement.

Other objects and adavntages will in part appear andiripart will be. obvious from the ensuing description of the present preferred embodiment of the invention, taken in conjunction with the drawings in which:

Fig. 1 is a plan view of thecutting attachment shown as mounted in the bed plate of a sewing machine, of which a fragment is shown;

Fig. 2 is a front elevation,partly in section, taken on the line 22 of Fig. 1;

Fig. 3 is a bottom .plan view of theattachment shown in Fig. 1;

Fig. 4 is a perspective view of the yoke and the reciprocating'blade carried thereby;

Fig. 5 is a side elevationtaken on the line 5-5 of Figs. 1 and 3, the feed dog being omitted;

Fig. 6 is an enlarged fragmentary detail partly in section, of the blade tensionlng means;

Fig. 7 isa plan view showing the parts of the cutting device Visible from the top of the machine when the cover plate, of which a fragment is shown, is in place; and

Fig. 8 illustrates one type of work which may be performed on a zigzag machine equipped with the cutter of the invention, showing how the joined edges of both pieces of fabric are bound within the line of stitching.

While it is recognized that others have heretofore disclosed shear-action cutters for the same purposes as the present inventiomthe novel structure of my device is an improvement thereover in its simplicity, low cost of manufacture, its ready attachability to existing sewing machines and in its ability to maintain cutting efficiency over prolonged periods of the high speed operation which is characteristic of modern types of sewing machines.

Referring to Fig. 1 there is shown at ill" a fragmentary portion of the bed plate of a sewing machine in which is an opening rimmed by a ledge II on which the regular throat plate of the machine rests. Where the device of the present invention is provided in the form of an attachment, the regular throat plate is removed and replaced by the assembly about to be described, which carries the cutting mechanism. This mechanism is actuated by a modified feed dog which replaces the regular feed dog and differs therefrom in being provided with a pin or shaft which coacts with the cutting mechanism to impart-to it the up andv down motion which is given to the feed dog by the mechanism of the sewing machine.

The cutting mechanism of the invention is mounted ona support plate M having arr-aperture l5 through which the feed dog It and the movable blade of the cutter operate. Plate i l is also provided with screw holes I! positioned to correspond to the tapped holes already provided in the bed plate [9. The plate l4 may conveniently be made of sheet metal which is stamped out to provide two pairs of spaced apart downwardly extending lugs I5 and i9, best shown in Figs. 3, 5 and 6.

On the upper surface of the support plate i l a fixed blade 29, generally L-shaped, is secured by screws 2! inserted from the bottom of the plate as shown in Fig. 3. The edge 22 of blade is ground to form a shearing edge and is preferably slightly undercut.

Referring to Figs. 3 and 6, the lugs i9 are drilled to freely receive screws 26 which have smooth shanks or bearing portions 25 and are threaded for a short distance at their ends 26. The lugs l9 are drilled and tapped to receive the threaded screw ends 26 and the screws are held in place by lock nuts 28.

Pivotally mounted on the bearing portions 25 of screws 24 is a yoke, generally indicated at 30. Referring to Fig. 4, this yoke comprises two arms 3| and 32 joined together by a bridge portion on which, and preferably integral therewith, is a block 35 containing a horizontal slot 36. This block is grooved, adjacent the face of bridge member 34, to receive the tongue 38 of the movable blade 39 which is held in place by a clamping block 40 secured by a screw 4|. The shearing edge of blade 39 is indicated at 42 and cutting takes place between this edge and the edge 22 of fixed blade 20 when the movable blade is moved downwardly.

The ends of the arms 3i and 32 of the yoke 35 are drilled in alinement as shown at 4A to receive the bearing portions 25 of the screws 24 so that the yoke is pivotally mounted thereon. It will be noted that there is room between the lugs l9 and IQ for the yoke 30 to slide somewhat on its bearings in a direction normal to the shearing edge 22 0f the fixed blade.

Referring to Fig. 6, to urge the blade 39 toward the blade 29 a leaf spring 45 is mounted between the head of screw 24 and the lug l9. The screw head is not tightened against the lug sufficiently to prevent free movement of the spring together with the yoke as it moves on its bearings. The other end of spring 45 is attached to the outer end of arm 32 by a screw 46 inserted in a tapped hole 5 which extends into the bridge member 35. By tightening or loosening screw 46, the tension applied to the yoke by spring 45 may be varied and thus the optimum shearing action may be obtained. Wear of the blades is taken up automatically by the spring 45.

As is well known in the sewing machine art, the feed dog [6 is given a four motion action through the medium of the feed bar indicated at 59 in Fig. 2, which bar moves backward and for- 6 ward and is in turn moved up and down by an arm 5| attached to an oscillating shaft. The feed dog I6 is formed on the end of a U-shaped bracket 52 (see Fig. 3) which is fastened to the feed bar by screws 53. Thus the feed dog of the sewing machine is readily removed and in the practice of the present invention it is conternplated that the regular feed dog will be replaced by another which has been modified by the addi tion of a pin 54 to the end 55 of the bracket 52. Pin 54 is so located and of such a length as to extend into the slot 36 of the block 35 which forms part of the yoke 39. When the machine is operated the up and down motion of the feed dog will thus be imparted to the yoke to reciprocate the blade 39. The backward and forward motion of the feed dog will merely result in the pin 54 sliding in the slot 36.

As shown in Fig. 2, the support plate I4 is covered over by a plate 58 which preferably extends from the left edge of the bed plate of the machine somewhat to the right of the right edge of plate l4 and for a substantial distance in front and to the rear of said plate, thus forming a smooth working platform. Referring to Fig. 7, it shows all that is visible of the cutting apparatus and the feed dog when the apparatus is completely assembled. Plate 58 is slotted in the manner usual with throat plates to receive the feed dog and is provided with an L-shaped opening closely surrounding three sides of the fixed blade 2|] and leaving a slot to the right of it through which the reciprocating blade 39 operates. The end 59 of this opening is in the form of a clover leaf surrounding the tip 60 of the fixed blade 29. This form of opening is one suitable for use with a zigzag machine, the needle passing downwardly therethrough on either side of the tip to form the stitches which slip off from below the tip in the 5 space provided. The extension of the blade 29 to a point beyond the line of stitch formation serves to support thin fabrics from below while they are being sewed. As will be appreciated, the width of zigzag stitching may be adjusted by regulating the vibrations of the needle from zero to the maximum provided in the particular machine and in the case of very narrow stitches, it may be that they are completely formed on one side or the other of the tip 60 but in the ordinary case the needle will pass through the goods first on one side and then on the other side of the tip.

It will be noted particularly (Figs. 7 and 8) that the cutting of the fabric passed beneath the cutting edge 42 of the reciprocating blade 39 takes place immediately in advance of the sewing and preferably just inside of the line of stitching so that the cut edge of the fabric is bound down by stitching as shown in Fig. 8. The needle is shown at 6| in the process of forming a zigzag stitch 62 which extends over the left edge of a lace trimming 63 being sewn onto a base fabric 64. As the material progresses through the machine blade 39 trims off the right edge of fabric 64 and the stitching 62 binds down the cut edge 65. The cut off material is shown at 66.

Referring particularly to Fig. 2, it will be seen that the only part of the cutter extending above the upper surface of the cover plate 58 is the shearing blade of the reciprocating cutter 39. In the sewing of applique, inserts and the like to fabric, the fabric itself is fed along the surface of the plate 58 and underneath the shear blade of cutter 39 while the material being applied or inserted is fed over the shear blade and thence under the presser foot 61. As the base material is run through the machine, it will be cut immediately in advance of the point where applique, inserts or the like are stitched to it, the portion 66 of the material which is cut off being carried along under the finished work by the conjoint action of the feed dog and presser foot. The presser foot is preferably so formed as partially to surround the movable blade 39, the outline of one suitable form being shown in dotted lines in Fig. 7. A presser foot having an edge guide for the inserted or applied material, such as that described in Patent No. 1,177,138, may be used with very desirable results.

The novel combination of elements hereinafter 5 claimed and in particular the yoke mounting for the reciprocating blade and the I spring tensioning means for the yoke-will be seento have several advantages. A very stable and rigid support for the moving blade is provided which maintains the desired *relationship 'of the shearing blades at all times. Any bearing wear in the yoke support has no appreciable efiect on the relative positions of the blades. Thetensioning means compensate for any blade wear continuously without altering the bladerelaticnship and is, very easily adjusted by means of a single screw. The complete cutter is self-contained and removable as a unit. If taken out :and the. regular throat plate replaced, the machine i s-ready .to operate without the cutter. Conversely, the cutter is quickly and easily placed in any machine, together with the modified feed dog, all in a matter of minutes, eliminating any loss of use of the machine during alteration.

It is to be understood that the specific embodiment herein particularly described is for purposes of illustration only and that the invention is to be construed broadly within the purview of the appended claims.

What is claimed is:

1. A shear-action cutter for a sewing machine comprising, a support plate having an opening, a fixed blade mounted on said support plate and having a shearing face extending over said opening, a yoke having two arms joined to the opposite ends of a bridge member which extends beneath said blade, the free ends of said arms being pivotally mounted on said support plate, and a reciprocating blade carried on said bridge member in shearing relation to the fixed blade.

2. A shear-action cutter for attachment to a sewing machine normally equipped with a throat plate, comprising, a support plate shaped to take the place of said throat plate in the machine, said support plate having an opening, a fixed shear blade secured to the support plate and extending over said opening, a yoke having two legs and a bridge member which passes beneath said opening and said blade, said legs being pivotally mounted on the support plate on either side of said opening, and a reciprocating blade mounted on said bridge member in shearing relation to said fixed blade, whereby oscillation of said yoke will produce a shearing action between said blades.

3. A shear-action cutter for attachment to a sewing machine normally equipped with a throat plate and a four motion feed dog operating therethrough, comprising, a support plate shaped to take the place of said throat plate in the machine, said support plate having an opening through which the feed dog operates, a fixed shear blade secured to the top of the support plate and extending over said opening, a yoke having two legs and a bridge member which passes beneath said opening and said blade, said legs being pivotally mounted on said support plate on either side of said opening, a reciprocating blade mounted on said bridge member in shearing relation to said fixed blade, said yoke having a horizontally slotted portion, and a pin carried by said feed dog and coacting with said slotted portion to oscillate said yoke and produce a shearing action between said blades.

4. A shear-action cutter for a sewing machine which has a feed dog, comprising, a support plate having a central opening through which. said feed dog operates, a fixed blade having a shearing face and mounted on said plate adjacent said opening, a yoke having two arms connected to opposite ends of a bridge member which extends beneath the fixed blade, the ends of said arms having axiallyialined openings, alined axles carried by saiduplate and extending through theopenings in the arms, atreciprocating blade carried on said bridge member in shearing relation to the fixed blade, and resilient. means for urging said yoke along saidzaxles in a direction to press the reciproeatingzbblade against the fixed blade.

.5. A shear-action cutter for a sewing machine havingafour motion feed dog, comprising, a support having an opening through which said feed dog operates, a'fixedbladehaving a shearing face and-mounted- .on said support, a yoke having two arms joined. to opposite ends of a bridge member which extends beneath said blade, alined axles carried by saidsupport, the free end of said arms being pivotally mounted on said axles with freedom to move'axially thereon, a reciprocating bledencarried on said "bridge member intermediate its ends in shearing relation to the fixed blade, a leaf sprin adjustably fixed at one end to said yoke in the vicinity of said bridge member and movably secured at the other end to said support and adapted to press said reciprocating blade against said fixed blade, and a connection between said feed dog and said yoke adapted to transmit the up and down motion of the feed dog to the yoke to operate the cutter.

6. A cutting attachment for use in a sewing machine of the type having a bed plate, a throat plate removably mounted thereon and four-motion mechanism for actuating a feed dog which operates through apertures in said throat plate, said attachment comprising, a support plate adapted to replace said throat plate, a yoke having two arms and a bridge piece and pivoted at the ends of its arms to the under side of said support plate, a fixed blade secured to the support plate with a shearing edge extending in the direction of feed, a moving blade mounted on the bridge piece of said yoke in shearing relation to the fixed blade, said yoke having a slot, and a pin carried by said feed dog and coacting with said slot to impart to said yoke the up and down motions of the feed dog to oscillate said yoke and produce a shearing action between said blades.

7. A cutting attachment for use in a sewing machine of the type having a bed plate, a throat plate removably mounted thereon and four-motion mechanism for actuating a detachable feed dog which operates through apertures in said throat plate, said attachment comprising a sup port plate adapted to replace said throat plate, a yoke having two arms and a bridge piece and pivoted at the ends of its arms to said support plate, a fixed blade secured to the support plate with a shearing edge extending in the direction of feed, a reciprocating blade mounted on the bridge piece of said yoke in shearing relation to the fixed blade, said yoke having a horizontally extending slot, a modified feed dog adapted to replace said detachable feed dog and having a projection adapted to coact with said slot to impart to said yoke the up and down motions of the feed dog to oscillate said yoke and produce a shearing action between said blades.

8. In a. shear-action cutting device, in combination, a yoke having two spaced apart arms joined to opposite ends of a connecting bridge, a reciprocating blade removably fixed to said bridge, a support having two spaced pairs of spaced apart lugs, a bearing member mounted in each pair of lugs, said arms being pivotally mounted on the bearing members and shiftable axially thereof through a short distance, a leaf spring attached at one end to said yoke at a point adjacent said bridge and rotatably secured at the other end to said support under a tension adapted to urgesaid yoke axially on its bearings, a fixed blade removably attached to said support in a position to be pressed against by the reciprocating blade under the influence of said spring, and means for oscillating the yoke to produce relative shearing movement between said blades.

9. In a shear-action cutter for use with a zigzag sewing machine having a laterally vibrated needle, said cutter comprising a support plate having a needle opening, a fixed shear blade mounted on said plate adjacent said opening, and a reciprocating shear blade arranged in shearing relation to said fixed blade, said fixed blade having a narrow point extending over said opening and underneath the path traveled by said needle in its lateral vibration, whereby a stitch is formed across said point and the work under said stitch is supported thereby.

VICTOR J. SIGODA.

REFERENCES CITED The following referen ces are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,117,607 Scott Nov. 17, 1914 FOREIGN PATENTS Number Country Date 433,675 Great Britain Aug. 19, 1935 

